The subject invention is directed toward the art of vascular catheters and to catheter manufacturing methods and, more particularly, to intravascular microcatheters of unitary construction provided with an integral continuous coiled wire reinforcement member, and to improved methods and apparatus for manufacturing multiples of such catheters from a continuous feedstock.
Angiographic catheters have been widely used for diagnostic purposes such as in conjunction with the injection of dyes or the like into arteries for the visualization of obstructions, ruptures, or other malformations. Diagnostic catheters are typically constructed with an embedded layered wire braid reinforcement system surrounding the lumen to provide torsional control and to strengthen the catheter body to better withstand high pressure injections.
Catheters of the type described above are shown in my prior U.S. Pat. No. 3,485,234, which issued Dec. 23, 1969. My prior U.S. Pat. No. 3,585,707, which issued Jun. 22, 1971 sets forth generally a method of manufacturing wire braid type angiographic catheters. In addition, my prior U.S. Pat. Nos. 5,738,742 and 5,972,143 describe how to manufacture a plurality of diagnostic catheters having unitary body and tip sections from a continuous feedstock. The teachings of the above prior patents are incorporated herein by reference.
It is likely that wire braid construction will continue to be useful in larger diameter catheters such as in the size range French 8 through French 4. However, in modern medical practice, the use of catheter device has been broadened to embrace many forms of interventional therapy. As examples, catheters are presently used in connection with placement of dilation balloons for opening obstructed coronaries and other vessels, for the placement of stints to xe2x80x9cpropxe2x80x9d open vessels, for introduction of anticoagulants to dissolve clots, and for introduction of coagulants to form clots to xe2x80x9cplugxe2x80x9d aneurysms or to seal off vessels feeding malignant tumors. The target vessels in the above procedures are typically located in the smaller vessels of the brain, kidney, liver, heart, and other organs. Braided wire catheters, however, are not well suited for applications that require a catheter size of French 3 or smaller. There is a need, therefore, for much smaller catheters that can be extended into the smaller target vessels.
One solution is to construct a catheter that uses a coiled wire reinforcement member within the catheter body as an alternative to the braided wire reinforcement construction scheme. Although the coiled wire construction results in some loss of torsion control, a significantly thinner overall catheter body is enabled. Catheters that include integral coiled wire members have an overall good pushability characteristic and typically do not kink as readily as braided wire construction catheters of the same diameter using the same wire diameter.
Another advantage is that coiled reinforcement wire catheters can provide a larger lumen size than braided wire type catheters relative to overall catheter body size. Since the reinforcement wire is overlapped in the braided construction as it is braided onto the inner catheter wall construction, the overall reinforcement layer thickness is at least twice as large as in the non-overlapping coiled wire type catheter using the same wire diameter.
U.S. Pat. Nos. 5,733,400 and 5,662,622 teach an intravascular catheter carrying a helical reinforcement member embedded within at least a portion of a tubular wall of the catheter. The catheter body is formed from separate sections which are connected end to end to provide successively increasing flexibility zones from the proximal end toward the distal catheter end. The catheter body is thin and therefore particularly capable of being advanced into small areas such as brain arteries for example, so that therapeutic agents may be delivered to locations deep inside the brain, which locations would be inaccessible to many other catheters.
However, the catheter taught in the above patents is expensive because the manufacturing method is very labor intensive. More particularly, turning to the flowchart illustrated in FIG. 1, the prior art manufacturing process 10 includes the steps of joining together a pair of tubular catheter reinforcement members in end-to-end, abutting relation 12. Next, in step 14, a UV curable adhesive is placed on the joined ends. In step 16, the joined ends are covered with a snug, non-adherent transparent sleeve. The adhesive is cured in step 18 and, thereafter, in step 20, the cover sleeve is removed. Additionally, preferably, the adhesive is cured using ultraviolet light and, accordingly, the sleeve is formed of a substantially ultraviolet radiation transparent material. In step 22, the joined reinforcement members are embedded into a tubular plastic catheter wall.
One major disadvantage of the catheter construction and method taught in the above patents is that the manufacturing method is highly time consuming and labor intensive. Further, the overall catheter assembly could be prone to failure because it is formed of a plurality of joined individual parts.
Accordingly, it would therefore be desirable to provide an interventional therapy type catheter having a continuous coil reinforcement member and that is of a substantially unitary construction. Further, it would be desirable to provide methods and apparatus for manufacturing multiples of such catheters from a single feedstock using a continuous process. In order to reduce manufacturing cycle time, it is desirable to wind the reinforcement wire directly onto the inner substrate layer of the catheter body in a continuous manner and, thereafter, apply one or more subsequent catheter body layers to produce a large number of catheters from a single feedstock in an efficient manner with minimal labor demands.
The subject invention provides a unitary intravascular microcatheter with a continuous embedded helical coil reinforcement member and methods and apparatus for manufacturing same at a reduced manufacturing cost by enabling multiple catheters to be manufactured from a continuous feedstock. The overall construction of the subject microcatheter device is unitary, making the subject device less prone to failure and easy to manufacture in multiples. The embedded reinforcement member forms a continuous helical path along the length of the microcatheter with a selected variable pitch angle to control the stiffness of the microcatheter at various portions. The pitch of the reinforcement member winding is selectively varied along the length of the catheter to provide a smooth transition between different catheter stiffness regions.
In accordance with a preferred aspect of the invention, there is provided methods and apparatus for manufacturing multiple catheters from a continuous feedstock. A selected length of an elongate cylindrical tube is provided, preferably, carried on an inner wire mandrel to prevent the tube from collapsing during the various manufacturing operations. A first selected length of the cylindrical tube is held stationary between a pair of spaced apart chuck members. A lead end of a reinforcement wire is spot-bonded to the tube and then wrapped onto the stationary portion of the first selected length of the cylindrical tube. The trailing end of the reinforcement wire is thereafter spot-bonded tothe tube. The wire wrapped portion of the cylindrical tube is then advanced relative to the pair of spaced apart chuck members to hold a second selected length of non-wire wrapped cylindrical tube stationary between the pair of chuck members. The reinforcement wire is then spot-bonded and wrapped onto a portion of the second selected length of the cylindrical tube held between the spaced apart chuck members using the procedure described above. The steps of advancing the cylindrical tube through the chuck members and then wrapping the reinforcement wire onto the tube is repeated for substantially the entire length of the elongate cylindrical tube to form a wire wrapped cylindrical tube with multiple wire wrapped sections spaced from one another by unwrapped sections. A continuous finish coating is then applied to the wire wrapped cylindrical tube. Lastly, the coated wire wrapped cylindrical tube is divided into multiple catheters by cutting the coated wire wrapped cylindrical tube at locations corresponding to unwrapped sections (i.e. sections without reinforcement wire wrapping) of the elongate cylindrical tube.
In its preferred form, the reinforcement wire is wrapped onto the cylindrical tube in a helical form along a path at selected angles relative to a plane perpendicular to a longitudinal axis defined by the cylindrical tube to provide regions of selected stiffness along the length of the catheter.
In accordance with a further aspect of the invention, the reinforcement wire is wrapped onto the cylindrical tube to form helical patterns in each of the catheters having a plurality of helical portions including at least helical first and second portions, the helical first portion having coils of a first pitch and the helical second portion having coils of a second pitch different than the first pitch. In that way, intravascular catheters are formed having portions of selected different flexibility characteristics.
In accordance with still a further aspect of the invention, there is provided a method and apparatus for manufacturing multiple catheters from a continuous feedstock. A selected length of an elongate cylindrical tube is provided, preferably, carried on an inner wire mandrel to prevent the tube from collapsing during the various manufacturing operations. A first selected length of the cylindrical tube is held taut between a pair of spaced apart reels including a tube pay-out reel and a tube take-up reel. A reinforcement wire is wrapped onto the cylindrical tube as the tube is advanced between the pair of spaced apart reels. The steps of advancing the cylindrical tube relative to the spaced apart reels and wrapping the reinforcement wire onto the tube are executed substantially simultaneously. The wrapping and advancing steps continue simultaneously, preferably for the entire length of the elongate cylindrical tube to form a wire wrapped cylindrical tube having a reinforcement wire wrapped in a helical form along a path at selected angles relative to a plane perpendicular to a longitudinal axis defined by the cylindrical tube to provide regions of selected stiffness along the length of the catheter. A continuous finish coating is applied to the wire wrapped cylindrical tube to hold the reinforcement wire on the tube and to form a coated wire wrapped cylindrical tube. Lastly, the coated wire wrapped cylindrical tube is divided into multiple catheters by cutting the coated wire wrapped cylindrical tube at selected locations.
In accordance with yet a further aspect of the invention, an intravascular catheter device is provided including an elongate flexible tubular inner wall defining a lumen of the catheter. The inner wall includes a first end defining a proximal end of the intravascular catheter and a second end defining a distal end of the intravascular catheter. A continuous coil reinforcement member is carried on the elongate flexible tubular inner wall and extends between the proximal end of the catheter and the distal end of the catheter. An elongate flexible tubular outer wall is provided covering the coil reinforcement member and carried on the inner wall substantially entirely between the proximal end of the catheter and the distal end of the catheter. In order to provide an intravascular catheter having portions with selected flexibility, the continuous coil reinforcement member is carried on the elongate flexible tubular inner wall along a helical path at selected varied angles relative to a plane perpendicular to the longitudinal axis defined by the catheter. Open helical winding pattern portions of the coil reinforcement member define flexible catheter portions. Conversely, closed helical pattern portions of the coil reinforcement member define relative stiff portions of the intravascular catheter. The pitch of the helical winding pattern is continuously selectively varied to provide a smooth transition between stiff and flexible regions along the length of the catheter.
The primary object of the invention is a reduction in the cost and time associated with manufacturing intravascular catheters with embedded helical coil reinforcement members.
Yet another object of the invention is the provision of an inexpensive intravascular microcatheter having a unitary construction that is less prone to failure during use. The microcatheter of the subject invention includes a continuous embedded helical coil reinforcement member that extends substantially between the proximal and distal ends of the catheter body.
A still further object of the invention is the provision of an apparatus for manufacturing intravascular microcatheters with embedded helical coil reinforcement members from a continuous feedstock.
Still other objects, advantages, and benefits of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed description.